1. Field of the Invention
Embodiments of the present invention relate to a blue electroluminescent polymer and an organo-electroluminescent device employing the same. More particularly, embodiments of the invention relate to a blue electroluminescent polymer having an indolocarbazole unit in the backbone of a polyarylene polymer, and an organo-electroluminescent device that offers improved emission efficiency and color purity.
2. Description of the Related Art
An organo-electroluminescent device (hereinafter “an organic EL”)is an active drive type emission display device using a phenomenon that when current is applied to fluorescent or phosphorescent organic compound layers (hereinafter “organic layers”), electrons and holes are combined in the organic layers to then emit light. Organic EL devices have various advantages, such as being lightweight, simple components with simplified fabrication processes, a wide range of colors with high luminescence. Also, organic EL devices can provide moving picture displays perfectly with high color purity and have electrical properties suitable for use in portable electronic devices at low power consumption and low driving voltage.
Such organic EL devices can be classified into low molecular weight organic EL devices and polymer organic EL devices, depending on their fabrication materials. Low molecular weight organic EL devices are advantageous because emissive compounds can easily be synthesized and purified to a high degree, and color pixels can easily be obtained. For practical application of low molecular weight organic EL devices, however, there still remains room for improvement in quantum efficiency and color purity, and there is a need to prevent crystallization of thin layers.
In polymer organic EL devices, a thin layer can be formed easily by spin coating or printing, so that such polymer organic EL devices can be fabricated in a simplified manner at low costs. In addition, organic layers formed during the manufacture of polymer organic EL devices exhibit good mechanical properties.
Such polymer organic EL devices, however, have several problems including low color purity, high drive voltage, and low emission efficiency. To overcome these problems, vigorous research is under way.